Elastic action cannon bore scavenger



Jan. 29, 1957 w. R. HOWARD ET Al. 2,779,241

ELASTIC ACTION CANNON BORE SCAVENGER Filed June 18, 1954 /NVENTOE S g uli 5 5gg/vans..

d P n W D am -mu im, m d w MT @ad Ll www o o 0 United States Patent VELAsTlc ACTION CANNON BoRE SCAVENGER L Wellington R. Howard, Falls church, va., and Walde Margulis, Albany, N. Y., assignors to the United States of America as represented by the Secretary of the `Application June 18,V 1954, Serial No. 437,894

11 claims. (ci. s91) .(Grand under Tine ss, U. s. code (1952), sec. 266) :there is inclosed a bore evacuator consisting essentially of :a flexible tube section having its ends clamped about the muzzle portion of the gun barrel to form with the wallithereof, an expansiblechamber. Forwardly and inwardlydirected bores yare provided through the barrel wall be. .tween the ends of the tube, whereby gases from the burniing propellant are forced under pressure into the aforo#A :said chamber after the inner ends of thepbore are uncovered by the projectile vas it traverses the barrel. VThe resulting distention of the flexibletubeuprovides a confined body of gas underv pressure which, after the projectile has left the barrel, is forced through the `aforesaid bore ito create la low'pressure area at the muzzle end of the barrel bore and purge the barrel of residual propellent gases forwardly through the muzzle. j y

*The .present application discloses .an improvement over the aforesaid pri-or application. i

' The present invention relates to a device' for purging objectionable andnoxious gases vand other residual lightweight matter lfrom thebore of a cannon. 1

' 'More particularly the'inven-ti-on relates to a device for evacuating the products voflcombustion of the pnopellent powder of a shell by= waylof.'` the muzzle end of a cannon to prevent them from entering the firing compartment of the motor carriage upon which the cannon is-mou'nted. i' The utilization of cannons andother artillery weapons on tanks and other self-propelled combat vehicles having closed cabs and -turrets for the.accommodation`of the.

stances escape by way of the muzzle after the projectilev has left the bore of the weapon, a goodly portion remains in the barrel bore. When the gun is' reloaded and Y retired the expanding gases of propulsioncause the gun to recoil in its mount. Upon counterre-coil a car'n` arrange-Y ment actuates an operating crank `to open Vthe breech block. At thesame time an extractor mechanism mounted on the breech block ejects the cartridge'through the j openl breech and linto the enclosed` space.v Thefact of Vejection also drags with the-cartridge case'a large por-l `of any royalty` 2,779,241 Patented Jam.Y 29, 1957 bac -or flareback, and vvarious devices have been sought to eliminate it, suchf'as for example, one in which a streamV of compressed air is directed into the breech and toward the muzzle .at the precise moment that the cartridge is ejected. These Ydevices however have been found to be extremely ineffective sincevthey are usually complex, unwieldy and extremely cumbersome. Additionally, they usually depend for action upon an intricate system of valves which very soon carbonize and become fouled up` with Vthe result that the eiciency of the mechanism is considerably reduced. v

It is .accordingly a paramount and important aim of this invention to provide a borevevacuator for gun barrels which eliminates the defects prevalent in the prior art devices. 1'

A further consideration impelling the need for this -inventionis to provide a bore evacuator device which is easily assembled into placeyeasily replaceable, simple and free ofvalves and other moving parts 'which tend to carbonize. v Y Itis another important motive to provide a bore evacuator which though not mechanically connected to the breech mechanism acts in timed relation to the -opening of the breech vend of theV gun to aspirate the residual particles and noxious gases by way of the muzzle end of the gun.

In the -direction last named this invention has as an object the provision of ailexible chamber concentric about the gun barrel and adjacent the muzzle end thereof, con# structed and arranged to trap a portion of the-gases of explosion under pressure. The trapped gases are then re# leased at the moment the breech end is opened for evacuation into the barrel andout of the muzzle end, whereby an aspirating effect is created upon a drop in pressure in the gun bore after the projectile has left it, to suck clean air into'the breech end to mix with and to sweep the noxious gases and residual lightweight matter out of the muzzle'end of the gun. Y f

Another object in view contemplated by this invention is the provision -of a flexible bore evacuator which is light in weight, easily replaceable, easily put in place or disassembled, free of valving and with a small number of elements and spare parts needed for repair, and in which special machining to the gun barrel for mounting the device is held vto a minimum.

`Additional objects, advantages and features ofthe invention reside in the construction, arrangement and combination of parts involved in the embodiment of the in-y vention as will appear from the following description and accompanying drawings wherein:

Figure l is a longitudinal section of the forward part of a gun barrel with the bore evacuator assembly in place. Figure 2 is a transverse elevation of one-of the split 'clamping rings for holding thebore eva-cuator assembly Vence charactershave been used to designa-te like or similar parts throughout the several views, reference character 12 represents generally a gun barrel of a semi-automatic cannon, having a major portion'of its forward end milled or turned down at 14, said milled portion extending be{ tween ashoulder 16 formed. thereby and the muzzle'end. The gun barrel is provided with `the usual longitudinal bore j 1S, and a plurality of circumferentially aligned equally `tion of thev undesirable produ-cts of burnt powder, smoke and noxious gases, `and the: products escapeV by way of the -open breech ,intoV ,the'crew compartment thereby result-` ing in the beforementionedudiscornfort, impaired .efficiency andserious danger `by .asphyxiation ofthe Agun crew.

lphen'ori'ienoniscommonly referredto' as VHashangularly spa-ced gas ports Ztl approximately midway between shoulder 16 and the muzzle end, and extending through 4the wall thereof in a forward and inward direction toward Vthe longitudinal axis ofV the'bore.'` 1

j i Thebore evacuator assembly per seeomprises a 1ongi` tudinally halved steel chamber `or canister 22, having' a wall. thickness Qf approximately. 1/s inch, arranged con.; centrically about reduced portion 14 and anged, for example, to provide means for .securing the halves in .assembled relation about-.the barrel., 'ln vlongitudinal QITQSS section and as clearly seen inFigure lchamber 22 comprises an enlarged central ellipsoidal'portion'zd merging into forwardly and rearwardly'extending throat portions or annuli Y26, 28, which loosely encircle thefreduced portion 14 to engage the. forward and rearward ends 30, 32 of a tlexible sleeve tube 34, also encircling the gun tube portion 14 snugly and coextensive in length .with the canister 22 so as to span gas ports Ztl. f Ends 3i), 32 ofexible tube 34 are provided with flap extensions 36, 38 which are turned over the ends of throat portions 26, 2810 thereby overlie the outer surface ofthe said throat Portions. The entire assembly is'the'nl snugly secured in place by split clamping rings 40, v42 each adapted to tit tightly about lap extensions 36, 38 respectively to encircle the throat portions`26, 28. The abutting free 'ends of rings 40, Y412 are provided withdownwardly depending pads or flanges 44, 46 provided with transverse holes to accommodate tightening nut and bolt assemblies 48, 50 in the wellknown manner. Throat 26 and ring 40 are provided with crimps 52, 54, and in like manner throat 28, and ring 42 areA provided with crimps 56, 58 to maintain the ap extensions 36, 38 fast within their respective clamps. The 'extreme end portions 69, 62 of throats26,

t 28 are provided with upturned rounded flanges 64, 66 to prevent undue wear and tear on the contacting portions of llexible tube 3,4. l

- When the device is assembled upon the gunrbarrel, the rearward-most end of the assembly abuts the shoulder 16 and is held in place by a retaining nut 70 whichvmay be screwed in -place to abut the forward end of the assembly, and which is provided with internal threads 72 to screw-threadedly engage external threads 74 4formed on the forward end of gun barrel 12 so that the bore evacuator device may be securely tightened into place against axial movement. As previously indicated, clamping rings 4b, 42 secure the device circumterentially about the gun barrel. Additionally, and as plainly seen in the drawing this arrangement provides gas tight seals to prevent the escapeof gases from thel canister. In order to prevent the hot exhaust gases from impinging directly upon flexible tube 3d, a split deflector ring '76 provided `with ears '78 for receiving a tightening screw and nut assembly 8) is secured about the gun barrel tube 12. The deflector comprises a .cylindrical portion 82 snugly engaging the gun tube just forwardly of gas ports 20,

andarearwardly and outwardly ared skirt portion 84 y extending over the gas ports to permit free access therethrough of the hot gases. To ensure that the tiexible tube 34 will expand freely, and to provide for the ready escape to atmosphere of gases which might .be entrapped between the canister 24 and exible sleeve 34,. a pluralityy of-radial holes 56 are drilled through the canister wall.

Al brief operation of the device follows. As previouslyV described the weapon is semi-automaticin operation, that Y is, the breechY is vmanually opened to load a round, and

automaticallyopened to eject the cartridge case when the' `round is tired. Since the gun parts other than the tube and bore evacuator are conventional and wellknown,

to this. .the.1;z'r iecti1e..hasr already. left the muzzle. cf. 1.1.15?. gun and the pressure of the gas in the gun bore has dropped considerably below the pressure of the lgas entrap'ped in the flexible tube. The drop in pressure in the gun bore permits the release of entrappedgas by way of gas ports 20, and the gas proceeds forwardly and then axially out of-"the muzzlewto Yform a low pressure area forwardly 'in the bore and adjacent the muzzle to causefclean air to rush from vthe. gun compartment by way of the. breech block (not shown). which has since opened, to evacuate the noxious gases and residue particles from the bore by way of the muzzle end. i

The'flexible gas 'container is an important feature of this invention since. it permits the Ventrapping or storing of gases at a lower pressure Ywithout the need for valves. Any of the well known natural orl synthetic rubbers or elastomers which are resistant to the noxious gases emitted bythe explosive propellant Vmay be suitablesuch as. for example, neoprene Type/"W (Dupont Report No.l 50.-2,v August 1950, page 163) compounded with carbon black; (semi-reinforced furnace) of approximately 50 durometer hardness, or neoprene, compounded withbutyl rubber in'the ratio of approximately 70 percent neoprene to 3.0 percent butyl. Due tothe elastic action of the container the period of .gasfexhaustion is increased to provide more. efcient evacuation, and the gases are delivered from the containerl at a more nearly uniform pressure to thereby establish a'steady ow condition of longer duration than would be obtained with a xed canister. Moreover the simply formedlelastic sleeve, outer container and clamping. rings are'relatively cheap to manufacture and assemble, and 'are soconstructed and arranged to provide gas seals effectively and with a minimum amount of machining of the parts as well as'the barrel surface. Additionally theA bore evacuator .device represents a structure whichisf` light in weight, a conditionwhich is always beneficial in gun mount design since it shifts the center 0f gravity .of

' the gun breechward to provide better gun stability. Also they are not deemed necessary to describe the invention and have not been shown. In a typical weapon, the pror pellent powder the cartridge case (not shown) is ignited Y v Y andfupon counterrecoil -a cam arrangement actuates an operating crank'to open the breech block, and tov place into'motion extractor mechanism Vtorejecting the cartridge' through the open :breech and `into the crew space. vPrior bullets or shrapnel.

Although a particular embodiment of the invention has i been described and illustrated, it is intended merely to be exemplary.Y Other modieations to the structure disclosed are obvious and` may-tbe'` made "without departing from the spirit and scope of the invention as set forth in the subjoined claims. Y f

1. A device for aspirating noxious gases from the muzzle end of a gun barrel comprising, elastic means forming a pressuretight chamber secured to the exterior surface of said barrel adjacent the muzzle .end thereof, there vbeing a plurality of gas ports formed in the wall of Said barrel providing communication between said bore and said chamber, said elastic means expanding to entrap a portion of the gases of ypropulsion of a. projectile red inl said barrelrvsaid ygas ports releasing said entrapped airto induce vlluidflow in a forward axial direction upon aldrop in pressurein said bore.

2. The device of claimrl and including a rigid container 3.l The device ofclaim l said gas ports being inclined i inwardlyfand vfrorwardlyftoward the muzzle `end of said barrel.v Y Y 4.-'A.`deyice Vfor evacuating from. the bore'of arearm -tube 'residual gases produced bythe firing of cartridge therein, `and comprising, VVanelastic storage compartmentV sealed tothe outerV surface ofgsaid tube, a xed con# tainer secured to saidtubeJ-outwardly of said'c'ompartment,` there being a plurality of circumferentially'aligned gas 'ports through the wall AQtf'said [tube land' inclined toward the muzzle fend thereof; said ports providing 1Communicationl between said bore and said compartment.

5. In a cannon having a barrel with a longitudinal bore, a device for evacuating residual gases produced by the ring of a cartridge therein and comprising, an elastic sleeve snugly surrounding said barrel and having its ends secured in gas tight engagement about said barrel, there being a plurality of circumferentially aligned gas ports through the wall of said barrel and intermediate the ends of said sleeve.

6. The device of claim wherein said gas ports are inclined toward the muzzle of said barrel.

7. The device of claim 6, and including a rigid multiperforated container concentric about said sleeve and said barrel, and secured to said barrel adjacent the ends of said sleeve.

8. In a cannon having a barrel provided with a longitudinal bore, the forward end of said barrel having a reduced cylindrical surface forming a shoulder, an elastic sleeve snugly surrounding said reduced cylindrical portion intermediate said shoulder and the muzzle of said barrel and having one end abutting said shoulder, there being a plurality of gas ports in the wall of said barrel and intermediate the ends of said sleeve, a rigid canister concentric about said sleeve, said canister comprising a bulbous central portion and reduced end portions, each said end portion adapted to overlie a corresponding end portion of said sleeve, a split clamping ring snugly encircling each said end portion, means for drawing each of wardly toward the muzzle end of said barrel.

10. The device in claim 8, the ends of said sleeve having flap extensions integral therewith and adapted to overlie the outer surface of said reduced end portions intermediate said clamping rings.

ll. The device in claim 8, and including a deecting ring encircling said barrel immediately forwardly of said gas ports, said deecting ring comprising a rearwardly opening flared out portion extending over the outer ends of said gas ports.

References Cited in the le of this patent UNITED STATES PATENTS 515,064 Unge Feb. 20, 1894 FOREIGN PATENTS 531,143 Great Britain Dec. 30, 1940 

